IEC 61249-2-22:2005

Overview

IEC 61249-2-22:2005 is an international standard published by the International Electrotechnical Commission (IEC) that specifies requirements for reinforced base materials used in printed circuit boards (PCBs) and other interconnecting structures. Specifically, it covers modified non-halogenated epoxide woven E-glass laminated sheets with defined flammability properties, tested using the vertical burning test, and includes copper-clad versions.

The standard applies to laminated sheets with thicknesses ranging from 0.05 mm to 3.2 mm. The materials achieve their fire retardancy through integrated phosphorus compounds and/or aluminum hydroxide as fire retardants within the polymeric matrix. These materials are designed to operate reliably with a glass transition temperature (Tg) between 150 °C and 190 °C.

Key Topics

• Materials and Construction: The base materials consist of epoxy resins that are chemically modified to be non-halogenated and enhanced for flame resistance. Reinforcement is provided by woven E-glass fabric, providing mechanical strength and stability.

• Flammability: The vertical burning test ensures the laminates meet strict fire safety requirements. Phosphorus compounds and aluminum hydroxide retardants enhance flame resistance without halogenated additives, promoting environmentally safer materials.

• Copper Clad Properties: The standard governs copper foil lamination quality, adhesion properties, and non-electrical characteristics such as appearance, thickness consistency, flatness (bow and twist), and machinability (punching and routing).

• Electrical & Mechanical Properties: It defines criteria for electrical insulation, flexural strength, and moisture absorption, critical for reliable PCB performance under various operating conditions.

• Dimensional Stability: Stability requirements ensure minimal warping or distortion, critical in high-precision electronic assembly.

• Quality Assurance: The standard outlines rigid quality control systems, including qualification, conformity inspections, and certification to guarantee consistent product performance.

Applications

IEC 61249-2-22:2005 material specifications are optimized for high-performance printed circuit boards and interconnecting structures where:

• Fire safety is a priority, especially in telecommunications, aerospace, automotive, and industrial electronics.

• Environmental concerns require non-halogenated, flame-retardant laminates.

• High thermal resistance and mechanical durability are needed, with Tg values supporting robust thermal cycling and assembly processes.

• High dimensional and electrical stability are essential for complex multi-layer PCB designs and miniaturized electronics.

This standard supports the development and use of safer, more reliable PCB substrates that comply with international safety and environmental regulations, promoting sustainable manufacturing practices.

Related Standards

• IEC 61249 Series - Covers a broad range of base materials for printed boards, including other types of reinforced laminates with different resin systems and flammability ratings.

• IEC 60335-1 - Safety standards relating to electrical appliances, reinforcing the need for non-halogenated, flame-retardant PCB materials.

• UL 94 - Describes flammability test methods frequently referred to in PCB material evaluations.

• IPC-4101 - Industry specifications for base materials in printed circuit boards often reference IEC standards, ensuring cross-industry harmonization.

Summary

IEC 61249-2-22:2005 defines rigorous requirements for modified non-halogenated epoxy woven E-glass laminated sheets with copper cladding used in printed circuit boards, emphasizing flammability, mechanical robustness, and electrical properties. Its adoption ensures PCB materials meet international fire safety expectations without the use of halogenated retardants, aligning with modern environmental and performance criteria. Engineers, manufacturers, and designers rely on this standard to source or produce PCB base materials that deliver durability, safety, and regulatory compliance in advanced electronics applications.